Glass lined agitated reactors are widely used by fine chemicals and pharmaceutical industry. Heat transfer area is one of the key criteria that determine the efficiency of a process, which in turn depends on the type of equipment used. These conventional glass lined reactors have very limited heat transfer area, in the range of typically 3 to 5 m2/m3 of reactor, wherein heat transfer area is estimated as [(perimeter×height)/(cross-sectional area×height)] and expressed as sq meter/cubic meter.
Stirred tank reactors (STRS) used in pharmaceutical and fine chemical industries are designed for providing and removing heat. This is done with coil or half coil with coolant passing through it, or using jacketed tanks. STRs with jacket or coils have heat transfer area of 60-80 (m2/m3). Further the improvement of heat transfer in stirred tanks cooled by helical coils is reported by Braz. J. Chem. Eng. vol. 20 no. 2 São Paulo April/June 2003. An improved reactor system for the carrying out of exothermic reactions of a gas or liquid, is disclosed in EP 0974395, additionally stirred-tank reactor and method for carrying out a polymerisation reaction is well established in U.S. Pat. No. 8,148,480.
To increase area, coils are immersed in the reactors. But coils occupy space, so size of tank has to be increased. Though heat transfer obtained is about 150 m2/m3, there is a limit up to which tanks sizes can be increased.
Glass lined reactors are needed for toxic and corrosive chemicals, but heat conductivity is compromised due to the low heat conductivity of glass. Therefore, reactions are carried out for very long periods of time, which is not desirable, especially when toxic chemicals have to be handled. SS reactors cannot be used to overcome this since they erode or corrode.
These limitations on heat transfer area as well as the absolute necessity to use glass lined reactors for toxic chemicals often compel industries to conduct reactions at lower temperature. This causes longer batch/residence times (more capital cost per unit product), lower yield and higher utility requirements (more operating costs per unit product).
The concentric tubes are employed in heat exchangers to improve the heat exchange/transfer rate, whereas the toxic and corrosive chemical reactions restrain the scope of the reactor. Some of the concentric tube reactors are listed herein, the Double-Pipe Heat Exchanger′ is reported by Jeffrey B. Williams in Project No. 1H Laboratory Manual Sep. 18, 2002.
Further triple tube heat exchanger is demonstrated in US 20100300663, whereas high-throughput microporous tube-in-tube microreactor described by Jian-Feng Chen et al. in AlChE Journal Volume 57, Issue 1, pages 239-249, January 2011.
To overcome the drawbacks of available reactors with regard to poor heat transfer area, limited scope of reactions, but yet retain the ability to perform reactions with toxic chemicals in glass lined reactors, the inventors have proposed a novel tube-in-tube glass lined reactor.